The invention relates to a process and an apparatus for manufacturing a composite strand formed by the combination of a plurality of continuous filaments of glass and continuous filaments of an organic thermoplastic material.
More specifically, the invention relates to a process, and to an apparatus for its implementation, wherein continuous filaments of glass and of an organic thermoplastic material are drawn from these two materials in the molten state and wherein these different filaments are combined to form a composite strand.
A process for manufacturing a composite strand according to this principle is known, and has been disclosed in U.S. Pat. No. 5,011,523. This patent describes installations comprising a die, from which continuous glass filaments are drawn, and a drawing head, which is supplied under pressure with an organic thermoplastic material, thereby producing continuous organic filaments. These different filaments, in the form of layers, or layers and strands, are combined in various ways to form a composite strand.
The '523 patent proposes an advantageous embodiment that consists of surrounding the glass filaments or the strand with the organic filaments at the time they are combined. The composite strand produced in this manner displays an advantage in that it prevents, or at the very least restricts, the friction of the glass filaments on the solid surfaces with which it comes into contact.
According to the '523 patent, this embodiment requires the implementation of an annular drawing head with a center opening through which the glass strand or filaments pass. From the description in the patent, this type of composite strand can be produced only by using a special installation.